CVE-2026-5474: NASA cFS Buffer Overflow Vulnerability

CVE-2026-5474 Overview

A heap-based buffer overflow vulnerability has been identified in NASA Core Flight System (cFS) up to version 7.0.0. The vulnerability exists in the CFE_MSG_GetSize function within the file apps/to_lab/fsw/src/to_lab_passthru_encode.c, which is part of the CCSDS Packet Header Handler component. Successful exploitation of this vulnerability could allow an attacker with adjacent network access to manipulate packet headers, potentially leading to memory corruption, application crashes, or arbitrary code execution.

Critical Impact

This heap-based buffer overflow in NASA's cFS flight software framework affects systems handling CCSDS packet headers. Attackers with local network access could potentially compromise satellite ground systems, mission control software, or embedded aerospace applications using this framework.

Affected Products

• NASA cFS (Core Flight System) up to version 7.0.0
• Applications utilizing the to_lab telemetry output module
• Systems implementing CCSDS Packet Header handling via cFS

Discovery Timeline

• 2026-04-03 - CVE-2026-5474 published to NVD
• 2026-04-07 - Last updated in NVD database

Technical Details for CVE-2026-5474

Vulnerability Analysis

This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the CCSDS Packet Header Handler, specifically within the CFE_MSG_GetSize function used by the telemetry output laboratory application (to_lab). The function fails to properly validate the size field extracted from CCSDS packet headers before using it in memory operations.

When processing incoming CCSDS packets, the telemetry passthrough encoder reads the packet size from the header without adequate bounds checking. This allows an attacker to craft malicious CCSDS packets with manipulated size fields that exceed allocated buffer boundaries, triggering a heap-based buffer overflow condition.

The vulnerability requires adjacent network access, meaning an attacker must be on the same network segment as the target system. This is particularly relevant in satellite ground station environments, mission operations centers, or development/test networks where cFS-based applications are deployed.

Root Cause

The root cause of this vulnerability stems from insufficient input validation in the CFE_MSG_GetSize function when processing CCSDS packet headers. The function extracts the packet size from the header structure but does not verify that this value falls within expected bounds before it is used for subsequent memory allocation or copy operations. This oversight allows attacker-controlled data to influence memory operations, resulting in writes beyond the intended heap buffer boundaries.

Attack Vector

Exploitation requires the attacker to have access to the local network (adjacent network attack vector). The attack proceeds by sending specially crafted CCSDS packets to a system running the vulnerable cFS application. The malicious packets contain manipulated header fields that cause the CFE_MSG_GetSize function to return an incorrect size value.

When the telemetry passthrough encoder processes these packets, the oversized value leads to a heap-based buffer overflow. Depending on the heap layout and the attacker's ability to control the overflow data, this could result in denial of service through application crashes, corruption of adjacent heap objects, or potentially arbitrary code execution if the attacker can precisely control memory contents.

The vulnerability was reported to the NASA cFS project through GitHub Issue #952, however, the project has not yet responded to the disclosure.

Detection Methods for CVE-2026-5474

Indicators of Compromise

• Unexpected crashes or segmentation faults in cFS applications, particularly those using the to_lab telemetry module
• Abnormal CCSDS packet traffic on the network with unusual size field values
• Memory corruption artifacts or heap integrity check failures in cFS process memory
• Unexpected behavior in telemetry passthrough encoding operations

Detection Strategies

• Implement network monitoring to detect anomalous CCSDS packet structures with size fields exceeding normal operational parameters
• Deploy memory protection mechanisms such as ASLR and heap canaries on systems running cFS applications
• Configure application-level logging to capture packet processing errors in the telemetry output module
• Use SentinelOne's memory protection capabilities to detect and prevent heap-based buffer overflow exploitation attempts

Monitoring Recommendations

• Monitor cFS application logs for repeated parsing errors or buffer-related warnings in to_lab_passthru_encode.c
• Implement network intrusion detection rules for malformed CCSDS packets targeting cFS endpoints
• Enable heap corruption detection tools during testing and development phases
• Configure alerts for unexpected process terminations of cFS-based applications

How to Mitigate CVE-2026-5474

Immediate Actions Required

• Restrict network access to systems running NASA cFS to authorized personnel and systems only
• Implement network segmentation to isolate cFS applications from untrusted network segments
• Deploy application-level firewalls or packet filters to validate CCSDS packet structure before reaching cFS applications
• Monitor the NASA cFS GitHub repository for security patches and updates

Patch Information

As of the last update on 2026-04-07, no official patch has been released by NASA for this vulnerability. The project was informed of the issue through GitHub Issue #952 but has not yet responded. Organizations using cFS should monitor the official repository for updates and consider implementing the workarounds below until a patch becomes available.

For tracking purposes, additional technical details can be found at VulDB #355078.

Workarounds

• Implement custom input validation for CCSDS packet size fields before processing with CFE_MSG_GetSize
• Deploy network-level filtering to reject CCSDS packets with size values outside expected operational ranges
• Isolate cFS applications on dedicated network segments with strict access controls
• Consider disabling the to_lab telemetry passthrough module if not required for operations
• Run cFS applications with reduced privileges and enable operating system-level exploit mitigations (ASLR, DEP, stack canaries)

Organizations should implement defense-in-depth strategies combining network segmentation, input validation, and runtime protection mechanisms until an official patch is released by NASA.